The present invention relates in general to compression mount receptacles for mounting components to circuit boards, and in particular to a high frequency compression mount receptacle for mounting test and burn-in sockets to circuit boards.
Connectors, receptacles and interposers have been provided for mounting various components to printed circuit boards. Component manufacturers typically perform burn-in testing of electronic components using test and burn-in sockets to mount components to circuit boards which connect the components under test to circuitry. The test and burn-in sockets are subjected to repeated use for testing different components, and test pins for the test and burn-in sockets are subject to breakage and bending as components are loaded and removed from the test sockets. When test pins for the sockets are damaged, an entire socket often has to be removed to replace the damaged test pins. Replacement of a single test pin can thus require that a large number of solder connections be re-flowed to remove the test socket, which can result in damage to the circuit board to which the test socket is mounted. In order to accommodate various size and alignment tolerances, test pins for test and burn-in sockets have been provided with tails which extend downward for mounting in through-holes of a through-hole style circuit boards. Due to the small contact lead or land spacings of current electronic components, through-hole style circuit boards are used for mounting test sockets to circuit boards. Although surface mount technology may also be used, size and cost limitations also require that the test and burn-in sockets be soldered to the circuit boards.
Helical coil compression springs have been used to provide compliant connections in electric circuits. However, helical coil compression springs are not suitable for use as electrical contacts in high frequency circuits, since the coils of the springs are electrical inductors which have the undesirable effect of smoothing out high frequency signals. In the past, when component contact spacings were larger, metallic tubular electrical contacts, commonly referred to as pogo pins, were used to provide compliant connections between test circuits and components under test. Typically, the tubular contacts included a pair of metallic sleeves which were telescopically joined to provide compliant electrical connections which could accommodate different distances between mating contact lands. Helically coiled compression springs were mounted inside of the pairs of telescoping tubular members. The metallic, telescoping tubes provided an electrical path around the interiorly disposed coil springs, and the interiorly disposed coil springs provided compliance, pushing the respective pairs of metallic tubes apart under compressive loads.
A compression mount receptacle is provided for mounting test and burn-in sockets for connecting components under test to test circuitry. The receptacles include a plurality of helical coil spring contacts which have active portions defined by of loosely wound coils which provide compliance for accommodating tolerances and changes in distances between the test and burn-in sockets and the circuit boards. The coil spring contacts further include first and second contact end portions, with some of the contact end portions being formed of close wound coils in which edges of adjacent coils are in contact to provide lineal circuit paths. Conductive contact tangs extend within respective ones of the coil spring contacts and provide a substantially lineal circuit paths which electrically connect between respective ones of first and second electrical contacts, providing a shortened contact circuit across the loosely wound helical coils of the coil spring contacts. In one embodiment, the coil spring contacts are defined by helically wound, conductive wires having first end portions formed to extend within the loosely wound coils and contact the close wound coils to provide the contact tangs. The test and burn-in sockets include contact lead tails which extend from beneath the sockets for insertion into the coil spring contacts, to press against the contact tangs located inside of the contact springs.
In alternative embodiments, the contact tangs may be provided as separate members from the helical coil compression springs, with the contact tangs extending interiorly within respective ones of the coil spring contacts. In one embodiment, the contact tangs each have a head and a shank. The head contacts a contact of a test socket or of a component under test, and the shank extends to contact a close wound end portion of the coil spring contact. In another embodiment, a contact button is disposed within a housing of the receptacle and engages between an end of the active portion of the springs and the contact of the test socket or a component under test. A contact tang extends from the contact button to the opposite end of the coil spring, preferably directly engaging close wound coils.